The present invention relates generally to a composition useful in forming synthetic surfaces simulating various natural stone substances such as field stone, granite, marble and the like. More particularly the present invention relates to compositions comprising organic resin materials capable of being sprayed onto horizontal and vertical solid surfaces which, when cured, simulate various natural substances such as granite and which exhibit improved flame resistant properties.
Processes currently exist for forming synthetic materials and surfaces, which mimic the appearance of various natural substances such as stone, marble and the like. Such materials are commonly used in the manufacture of floor and other types of tiles, shower enclosures, countertops, sinks, architectural facings, ornamental objects, and generally for any other purpose that marble, stone or the like are used.
One such example is a process utilizing a laminated sheet of material marketed under the trademark FORMICA. Such material is formed in large sheets and then cut and applied to the desired surface by adhesive or the like. Such sheets can be manufactured in solid colors or in various patterns, some of which simulate various stone or other textured materials.
Another example is a process for preparing a material, which is commonly referred to as “cultured marble”. “Cultured marble” is formed by first creating a mold of a desired shape, spraying the internal mold surface with a gel coat and then filling the mold with a conventional casting resin. Pigments are added to the resin to give it the desired color or pattern. After the resins have set, the mold is removed with the surface facing the mold forming the outer surface of the finished product.
Although many of the prior art methods for creating synthetic surfaces simulating stone and the like are generally acceptable, there is a continuing effort to develop compositions which give rise to more uniform, smoother coatings as well as surfaces which more closely simulate the various natural materials such as polished field stone, marble or granite and the like. Accordingly, there is a continuing need and desire to improve upon existing methods. Another object is to provide for coating compositions, which are flame resistant, and yet maintain the impact resistance and flexural strength required to provide simulated stone coatings in such applications as kitchen counters. It is known that flame retardency can be increased by the addition of increasing amounts of inorganic filler in the matrix resin. Such increases in filler amounts in the matrix resin, however, result in the embrittlement of the coating composition and do not result in a useful product.
Examples of suitable gel coatings may be found in U.S. Pat. No. 4,543,366, issued Sep. 24, 1985 to Smith, U.S. Pat. No. 5,028,459, issued Jul. 2, 1991 to Lathrop and U.S. Pat. No. 4,664,982, issued May 12, 1987 to Genovese, et al., the contents of each of which are herein incorporated by reference.
In order to obtain a simulated stone coating the resin matrix must contain solid fillers, which provide the stone appearance. Such stone fillers have densities which are much higher than the matrix resin density and thus tend to settle out and coatings do not provide the desired simulated stone appearance. Various approaches have been developed to address this problem. For example, Lathrop uses crushed stone aggregate having a density substantially greater than that of the gel coat. Thus, to get a three-dimensional display, multiple sequential layers of gel coat and matrix must be applied. The subject invention overcomes this problem by using particulates which are substantially equal in density with the matrix resin composition and by means of controlling the crosslinking reaction to prevent settling.
A similar problem was addressed in the context of cast molded granite-like artificial stone in U.S. Pat. No. 5,043,377, issued Aug. 27, 1991 to Nogi, et al. Nogi, et al. suspended cured thermoplastic chips containing a large proportion of filler within a thermoplastic resin casting composition and stated that chips and liquid matrix should be close to each other in specific gravity. However in spraying compositions more uniform results without settling are obtained by using thermosetting resins as matrix resins and controlling the rate of crosslinking and curing.
U.S. Pat. No. 5,476,895 issued to Akbar Ghahary discloses sprayable coating compositions based on the concept of using a thermosetting resin matrix and crosslinked resin granules containing inorganic fillers. The granules and the matrix have essentially the same density. Although such compositions are useful in spray applications they are extremely sensitive to variations in viscosity and frequently do not provide uniform thickness in allowing the coating to flow before it is sufficiently crosslinked to stay in place, this is particularly true when the coating composition is sprayed onto a vertical surface.
The subject invention provides compositions that have sufficiently high inorganic filler content to provide improved fire resistance over known equivalent compositions while at the same time providing compositions with increased rates of polymerization of the matrix resin when sprayed at room temperatures. This increased rate of polymerization of the highly filled compositions is accomplished without discoloring the matrix resin base and providing a more uniform simulated stone coating. The subject coating compositions can be sprayed, brushed, rolled or curtain walled directly onto a surface as a final over-spray or sprayed, or brushed rolled or curtain walled onto the inside surface of a mold and then backed with a substrate, such as fiberglass or resin.